Patients with localized ocular diseases or with ocular manifestations of systemic disease are examined clinically, and photographic documentation is made of significant findings. Biopsy specimens or autopsy eyes from these patients are examined by electron microscopy and histochemical stains. Studies are performed on patients with ocular manifestations of systemic diseases. Forty patients with acquired immunodeficiency syndrome (AIDS) were examined for ocular abnormalities. Twenty of these patients died and the eyes were obtained for culture and histologic examination. These patients have multiple opportunistic infections and neoplasms as the result of a severe depression of cellular immunity. Fifty percent of all patients with AIDS and 75% of the autopsy group have ocular signs attributable to AIDS. Ocular findings were confined to four major categories: cytomegalovirus (CMV) retinitis (10 patients), retinal cotton wool spots (11 patients), conjunctival Kaposi's sarcoma (2 patients), and neuro-ophthalmic motility abnormalities (3 patients). Cytomegalovirus retinitis was a significant cause of visual loss. Seven of 40 autopsy eyes had hand-motion or worse vision prior to the patient's death because of CMV and progressed to involve the entire retina in three or six months resulting in a gliotic retina membrane. Disseminated systemic histoplasmosis was observed in a patient with AIDS. In 3 patients, the effect of argon laser treatment was shown to be ineffective in halting the spread of cytomegalovirus in patients with AIDS. Immunohistochemical stains are performed on patients with retinitis pigmentosa and retinoblastoma to test for the presence of neuronal and glial proteins. Electron microscopy is also performed in selected cases.